Patent GB-565886-A (GB)
Title: Improvements in fusion welding
IPC: B23K9/035
Filed: 1943-05-27
Abstract: 565,886. Uniting by fusion. BABCOCK & WILCOX, Ltd. May 27,.1943, No. 8486. Convention date, Sept. 1, 1942. [Class 83 (iv)] In butt welding longitudinal or circumferential seams in metal members by fusion, particularly by the electric arc process, the base of the welding groove is backed'by a member of refractory material, and the part of the groove adjacent thereto is filled with a metal or alloy in powder form or in foil or strip form or a combination of such forms and is melted in the groove without fusing the backing member and additional molten metal is combined with the molten powder &c. to form a bead of weld metal uniting the members at the base of the groove. Slag from the electrode coating or from oxidation of the work is thus floated to the surface of the molten pool and slag trapped in the part is thus avoided. The backing member may consist of a core of silica sand bonded and baked and having a coating of carbon or graphite applied as a powder or as a graphite water mixture. The carbon &c. face does not fuse during welding and is chemically inert to slag so that the slag in the molten weld metal is prevented from reacting with the body of the refractory material. Further, the backing may be easily removed from the work after welding and the joint may be visually or radiographically inspected at intermediate stages and any faults remedied before the deposition of a large amount of metal. In a modification, the backing member may consist of a block of carbon or graphite. In joining ferrous parts, the powder &c. may be of pure iron or steel. In making a circumferential joint, the electrode is operated in the down hand position and the work is rotated step by step between welding operations and for welding parts of considerable thickness each section is preferably completed by depositing at least two layers thereon and allowing it to cool to about 800‹ F. before shifting the backing member to weld the next section. When the arc is interrupted, e.g. to renew an electrode, the end of each section is preferably tapered by chipping for a distance of about half an inch before restriking the arc and a small quantity of powder added. For welding in other positions of the electrode, the powder may be mixed with a non-slag forming binder. After the sections have been completed as above, the sections of the next layer are applied preferably staggered in relation to the sections upon which they are deposited. The remainder of the groove is then filled with weld metal in the usual manner. The joint has on its inner side a small ridge. Two tubular steel parts 10 may be supported with the lips 14 of the groove 16 slightly apart and with a counterbored part 20 to engage an arcuate refractory backing block 22 provided with a longitudinal groove 24. Iron or steel powder is sprinkled in a continuous layer along the groove 16 to fill it to a depth at least level with the top edge of the lips and preferably to cover the lips as shown at 26, prior to introduction of the weld metal from the electrode which is melted simultaneously with the powder. Any indication of carburization due to the carbon block may be avoided by increasing the amount of powder. The block 22 is secured by bolts 44 passing through the detachable sides 40 of a channel member 38 separated from a base member 48 by springs 78 which press the members 38, 48 in opposite directions against the work parts. To the member 38 is fixed a slotted guide 54 slidably engaging an intermediate slotted blade 60 secured to the member 48. The slots accommodate a wedge 72 for retracting the block 22. The wedge is secured by a pin 112 to a rod 110 having a straight length longitudinally movable in a slotted tube 84, which is secured by a removable locking pin 98 to a pin 86 with a reduced end 88 secured to the member 38 by a nut 90 and by a set-screw 92 engaging a flat 94 to prevent rotational displacement of the part 38 relatively to the pin. On the tube 84 is secured a coupling 102 which is secured by set-screws 106 to a replaceable section 104 having a notched end fitting into the end of the tube 84 so that the backing member may be moved into register with the welding groove. The rod 110 which operates the wedge 72 is connected by a coupling to an extension piece 122 fitted with a handle. The parts 50 of the base member 48 which engage the work parts are provided with grooves 52 to furnish a clearance for the inner bead of weld metal. Holes 32 are provided in the block 22 to receive removable pins 34 to extend through the gap 18 between the work parts to facilitate alignment of the groove 24 with the gap. Both pins may be used when making the initial adjustment, but for subsequent adjustments one of the pins is replaced by the welding bead engaging the groove 24. In welding plates, 'the backing member may comprise a grooved carbon block 128 carried by a channel member 130 supported by screws 132. This arrangement may also be used for curved plates as well as longitudinal and circumferential seams in large tubular bodies.